Vietnam is one of the countries in Southeast Asia that developed bronze casting and iron techniques early in its history. Around the middle of the 1st millennium BC, there existed three centers of civilization in Vietnam. These centers were the foundation for three ancient states and kingdoms that flourished and developed in and around several centuries BC and AD. They included the Dong Son culture (Van Lang, Au Lac States); Sa Huynh culture (Champa Kingdom); and Dong Nai, Oc Eo cultures (Phu Nam Kingdom). The Dong Son culture, with strong advancementof wet rice cultivation and bronze casting technique, soon created favorable conditions for early states of Van Lang–Au Lac to be established, opened a period for the first states to be formed and laid the foundation for Vietnamese cultural traditions to develop.